Post-9/11 Veterans from Operations Enduring Freedom and Iraqi Freedom (OEF/OIF) represent a clinically complex group who require non-stigmatizing and multidisciplinary interventions that effectively target their many comorbidities associated with mild TBI and posttraumatic stress disorder. Research indicates that a majority of combat Veterans experience difficulty in readjusting to civilian life after returning from combat including relationship difficulties, impulsive and dangerous behavior, increased substance use, and increased anger control problems. Mental health problems are frequently cited as driving these difficulties. Unfortunately, this group of Veterans has also been demonstrated to be highly resistant to mental health treatment and difficult to engage, showing high rates of appointment no-shows and scheduling difficulties. We propose this growing group of Veterans requires integrative, transdiagnostic (across diagnoses) interventions that will be appropriate for the range of treatment challenges they present while also being palatable and engaging. To address this treatment gap, we have developed the STEP-Home workshop for returning Veterans and demonstrated its feasibility and preliminary effectiveness in a recently completed RR&D SPiRE award (2014- 2016). In this Merit Review proposal, we propose to build on those findings and advance the development of the STEP-Home reintegration workshop to the efficacy stage in a multisite randomized controlled trial. STEP- Home is a 12-week, 2 hour/week reintegration workshop designed to assist all post-9/11 Veterans (with and without a history of psychiatric and/or neurologic diagnoses) with developing skills to improve their anger/impulse control and assist their reintegration to civilian and work life after the military. The core skills and content of the program are novel in their collective use and have not been applied to a Veteran population prior to our SPiRE feasibility study. We will conduct a multisite (TRACTS Boston; TRACTS Houston), randomized controlled trial of STEP-Home (26 workshops; 8 Veterans/workshop; total=208). We have two primary aims in this proposal. First, we will examine the treatment effects of STEP-Home on primary outcomes relative to an active control condition (Present Centered Group Therapy). Second, we will assess the maintenance of treatment effects for our primary outcomes. As an exploratory aim, we will examine treatment effects of STEP- Home on measures of mental health, functional and vocational status and cognitive secondary outcomes targeted indirectly in the workshop. Last, in a second exploratory aim, we will determine if the effect of treatment on the primary outcomes is mediated by the acquisition of core skills/key ingredients (problem solving, emotional regulation, attention training). The successful completion of the aims proposed has the potential to significantly improve skills to foster civilian reintegration in post-9/11Veterans. Furthermore, the STEP-Home SPiRE feasibility study demonstrated that the workshop also serves as a gateway for Veterans who are hesitant to participate in traditional mental health treatments to promote openness and engagement in additional, critically needed, VA services. Given the high rate of treatment resistance in this cohort, developing acceptable interventions that promote treatment engagement and retention, and open the door to future VA care, is necessary to improve functional status and to reduce long-term healthcare costs of untreated mental health illnesses.